Phelps led from start to finish and held off fast-finishing American team-mate Ryan Lochte down the final freestyle leg to win in one minute 54.27 seconds, just 0.04secs outside his own Olympic record.

It means Phelps is the first man to win the event at three consecutive Games and comes just 48 hours after he won his 18th and 19th Olympic medals to overtake Russian gymnast Larisa Latynina, who held the previous record with 18.

Lochte, who had been forced to settle for bronze in the 200m backstroke final 30 minutes earlier, took silver in 1:54.90, with Hungary’s Laszlo Cseh taking bronze. Britain’s James Goddard was seventh in 1:59.05.